Changes in postcranial morphology in modern American Whites

Secular change in stature and long bone lengths has been documented for the American population. In more recent years these trends have slowed or stopped altogether. This paper will examine secular trends in postcranial robusticity, shape of long bone shafts, and limb proportions. Data derived from the Terry Collection, the University of Tennessee Donated Collection and the Forensic Anthropology Databank. These individuals collectively have dates of birth from the 1840’s through 1980. Long bone lengths and shaft diameters of males and females, specifically, brachial and crural indices, and indices of robusticity and midshaft shape were examined. Analysis of variance using these dimensions by birth decade means reveals a trend towards gracilization, most pronounced in the femur. Tibiae become relatively longer over time, as shown by the crural index, and femur midshafts become relatively more anterior-posterior elongated. The brachial index in females reveals no consistent pattern, while males evidence a significant increase over time. Lengths of the humerus, radius and femur do not change significantly over time, however the tibia does exhibit significant increase for both males and females. Genetics and environmental factors play roles in how skeletal changes have occurred over time. While improvements in health care and nutrition have long been used to account for the secular changes in stature and bone lengths, marked differences in lifestyle likely play a role in the gracilization of postcranial elements.